White Clawed Crayfish Monitoring at Croft Castle

White Clawed Crayfish in bucket of water

We were joined by some special visitors, who completed a survey to find out if Croft's Fishpool Valley was still a successful habitat for a protected species known as White Clawed Crayfish. Some of our volunteers were lucky enough to go out and join them and have chosen to share their adventure with you.

White Clawed Crayfish are our only native species of crayfish; they are a protected species and are now classified as endangered. We have these native crayfish living in the streams and pools of the Fishpool Valley here at Croft, which is a designated Site of Special Scientific Interest due to the Crayfish .
A survey was carried out to show whether this protected species is still present, and how they use the site. The data is then used to help inform our management plan of the area to reduce any impact to our white clawed crayfish, if and when any future work is undertaken.
Dr’s Graham & Ann Hill were engaged as the survey team to undertake the Ecological Survey & Monitoring of the presence of crayfish in the Fishpool Valley. Three of us who are rangers here at croft were fortunate enough to accompany them during their visit to Croft.

Monitoring the white-clawed crayfish at Croft
Man holding crayfish in hand

On a fine Monday morning we all set off to show the survey team the water course that rises up from a spring at the top of Lyngham Valley. Having determined the most likely extent of the range of the crayfish, we accompanied the monitoring team as they began their survey.

" White Clawed Crayfish are our only native species of crayfish; they are a protected species and are now classified as endangered. "
- John Parsons


The survey had three elements; a daytime search, a night time search and the laying out of nets in the fishpools. We made our way up the valley scrambling over fallen trees and battling our way through nettles and brambles, following the streams that connect each of the fish pools. We eventually ended at the top pool adjacent to the Lime Kiln. During this first element of the survey we were shown where and how to look for crayfish. By late afternoon I think we, had a good idea of where the crayfish were most likely to be hiding along the stretch of the valley. Despite the fact that crayfish are nocturnal, we had actually come across several crayfish under stones and hiding in the stream banks.

" The pools as the sun was going down, the evening bird chorus, the fish jumping and the owls hooting their presence. "
- John Parsons


The night time survey is undertaken it was now a case of looking closely for movement and treading carefully as we made our way along the banks of the streams. We followed almost the same route although there was far more stumbling and scrambling than in the daytime.
By midnight when we finished, we had recorded more numbers than on the daytime search and notably more adult crayfish. This had been a very rewarding exercise, not least the sounds and views in the Fishpool Valley in the evening; the reflections in the pools as the sun was going down, the evening bird chorus, the fish jumping and the owls hooting their presence.
Above all it had been a revealing survey by Graham and Ann Hill, whose enthusiasm was infectious, and patience and willingness was quite exceptional. We await the publication of their analysis with great interest.

John Parsons, Volunteer Ranger